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whole canal, that is, its length and section, and 

 that which is determined by the locks, that is 

 by the lockage water* of one sluice, or by the 

 quantity of water which falls from the upper 

 into the lower channel every time a vessel 

 passes through a lock. These two volumes of 

 water lose by evaporation and filtration ; the 

 latter, which it is very difficult to estimate, 

 diminishes with time. The length and depth 

 of an oceanic canal in the New World, must 

 consequently have an influence oil the volume 

 of water necessary to fill it at the beginning, 

 when the excavations are just terminated, or 

 after having shut up the sluices, when repairs 

 are necessary; but the quantity of water which 

 should feed the canal annually, after making 

 allowance for the losses caused by the filtration 

 and evaporation, depends on the number of 

 the locks, or on the relation between the quan- 

 tity of the lockage water of one lock, and the 



* In the collected locks we must add the floating prison, 

 or the volume of water in which the ship floats, or is sus- 

 pended in its passage from one lock to another. (Prony, 

 in the works of M. Huene de Pommeuse, p. 23.) The con- 

 sumption of water is therefore greater in going up than de- 

 scending. The distribution of the falls, or the height of the 

 successive basins, have also an influence on the waste of 

 water in a canal, as M. Ge*rard has recently shewn. (An- 

 nates de Physique et de Chimie, 1823, Tom. xxiv, p. 137, and 

 Ducro&, Memoires, p, 39.) 



